Residual lung volume of female Thai adults

ABSTRACT: Lung volumes including residual volume (RV) are ethnicity-dependent parameters which are useful in clinical diagnosis of lung diseases and in assessing body density, and hence total body adiposity. The latter predisposes an individual to cardiovascular and/or metabolic diseases which are serious health problems worldwide. At present, RV of Thai people has not been reported. This study determines RV of young adult Thai women and proposes a prediction equation to compare it with other equations previously reported for the Asian population. A group of 161 healthy young women aged between 18 and 29 years were recruited for constructing and cross-validating the equation. RV was measured by an O2 dilution technique using a computerized spectrometer. Anthropometric variables were determined using a beam balance, a stadiometer, and bioelectric impedance analysis. The mean residual volume for the selected group of young Thai women is 1.18±0.23 l and best described by the equation RV=−3.236+0.024H+0.028A where H is the height in cm and A is the age in years. Goldman and Becklake's equation for Caucasians overestimated our RV whereas those of Ching and Horsfall, and Demura et al for Chinese and Japanese people, respectively, underestimated it. Chin's equation for Singaporeans yields similar value to the measured residual volume. The results confirm that residual volume is ethnically and geographically dependent. The equations for Thais and Singaporean of the same age and sex are comparable.